Preprints
https://doi.org/10.5194/acp-2021-898
https://doi.org/10.5194/acp-2021-898

  09 Nov 2021

09 Nov 2021

Review status: this preprint is currently under review for the journal ACP.

The impact of stratospheric aerosol intervention on the North Atlantic and Quasi-Biennial Oscillations in the Geoengineering Model Intercomparison Project (GeoMIP) G6sulfur experiment

Andy Jones1, Jim M. Haywood1,2, Adam A. Scaife1,2, Olivier Boucher3, Matthew Henry2, Ben Kravitz4,5, Thibaut Lurton3, Pierre Nabat6, Ulrike Niemeier7, Roland Séférian6, Simone Tilmes8, and Daniele Visioni9 Andy Jones et al.
  • 1Met Office Hadley Centre, Exeter, UK
  • 2College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
  • 3Institut Pierre-Simon Laplace, Sorbonne Université/CNRS, Paris, France
  • 4Department of Earth and Atmospheric Science, Indiana University, Bloomington, IN, USA
  • 5Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA
  • 6CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France
  • 7Max Planck Institute for Meteorology, Hamburg, Germany
  • 8Atmospheric Chemistry, Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
  • 9Sibley School for Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA

Abstract. As part of the Geoengineering Model Intercomparison Project a numerical experiment known as G6sulfur has been designed in which temperatures under a high-forcing future scenario (SSP5-8.5) are reduced to those under a medium-forcing scenario (SSP2-4.5) using the proposed geoengineering technique of stratospheric aerosol intervention (SAI). G6sulfur involves introducing sulphate aerosol into the tropical stratosphere where it reflects incoming sunlight back to space, thus cooling the planet. Here we compare the results from six Earth-system models which have performed the G6sulfur experiment and examine how SAI affects two important modes of natural variability, the northern wintertime North Atlantic Oscillation (NAO) and the Quasi-Biennial Oscillation (QBO). Although all models show that SAI is successful in reducing global-mean temperature as designed, they are also consistent in showing that it forces an increasingly positive phase of the NAO as the injection rate increases over the course of the 21st century, exacerbating precipitation reductions over parts of southern Europe compared with SSP5-8.5. In contrast to the robust result for the NAO there is less consistency for the impact on the QBO, but the results nevertheless indicate a risk that equatorial SAI could cause the QBO to stall and become locked in a phase with permanent westerly winds in the lower stratosphere.

Andy Jones et al.

Status: open (until 21 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Andy Jones et al.

Andy Jones et al.

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Short summary
Simulations by six Earth-system models of geoengineering by introducing sulphate aerosols into the tropical stratosphere are compared. A robust impact on the northern wintertime North Atlantic Oscillation is found, exacerbating precipitation reduction over parts of southern Europe. In contrast, the models show no consistency as to impacts on the Quasi-Biennial Oscillation, though the results do indicate a risk that the oscillation could become locked into in a permanent westerly phase.
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